Shock absorber construction



FE 1950 E. L. BEECHER I 29 9 SHOCK ABSORBER CONSTRUCTION Figled May 13,1947 "gym INVENTOR. [Z/GENE L. BEECHE/P HTTORNEY5 Patented Feb. 21, 1950SHOCK ABSORBER CONSTRUCTION Eugene L. Beecher, flleveland Heights, Ohio,as-

signor to The Gabriel Company, Cleveland, Ohio, a corporation of OhioApplication May 13, 194.7, Serial No. 7473695 .3 Claims. 1

This invention pertains to a-shock absorber-and, more particularly, :toa fluid-shock absorber.

Although the invention is applicable to various type shock absorbers, itis illustrated and explained herein by way of example as embodied in adirect .double-acting hydraulic shock 721bsorber. In certain of itsaspects the invention is an improvement on the shock absorber structuredisclosed in my Patent #2396227 dated March 12, 1946, .and the patentapplication of William G. Patriqui-n, Serial No. 750,901, now U. S.Eatent 2,487,471 filed May 28, 1947, in which patent and patentapplication the piston of the shock =absorber has a groove in which .ispositioned a pack-- ing ring mounted'on a continuous rigid carrier ring,the piston being formed in two parts toenable the ring to be positionedin the groove with the two parts being held in assembled relationship onand by the piston rod. In the construction therein shown, the piston rodhas a continuous circumferential groove spaced from one .end with theintermediate portion of the rod partially threaded. One part of thepiston is supported in the groove and comprises :a circular disclikemember having a central opening of less-diameter than the diameter ofthe rod and an eccentric opening of larger diameter than the diameter ofthe rod in overlappingrelationship with the cen tral opening forming abayonet-type slot in the member. The member for-ms the upper wall of thering groove and has passages through which the fluid of the shockabsorber may pass on reciprocation of the piston. The other part of the.

piston comprises an upper cylindrical member forming the base of thegroove and .a lower cylin- 1 disclike member whereby it is preventedfrom moving transversely on the piston rod. With such a construction,assembly is somewhat difficult because of the necessity of aligning thepins with the openings in the .disclike member. Cocking or tilting ofthe disclike member on the piston rod is possible becaus of the bayonettype opening and consequent limited bearing area of the side of themember onthe plston'rod groove wall.

Further, the area of the passages through the member is somewhat limitedandv nonsunjiformly distributed. Because the threading on the rod stopsshort of the groove, forming the threads is relatively diflicult.

An object of the present inventiton is the provision of a new andimproved shock absorber construction of the type referred to having apiston rod and a two-part pistonwhich enables a circumferentiallycontinuous bearing of a disc-like part of the piston against the upperwall of a groove on the rod, requires no alignment of the two parts ofthe piston, simplifies the threading operation of the lower end of thepiston rod, provides a greater and balanced passage area through thedisclike part, is simple in construction, and is easily assembled.

Another object of the invention is the provision of a new and improvedshock absorber construction including a piston rod having acircumflexential groove spaced from one end, :the portion of the rodbetween the groove and the end being completely threaded with threadshaving a root diameter at least equal to the diameter of the groovewherefore .a threading tool may advance into the groove on thecompletion of .the threading operation, thus prolonging the useful lifeof and enabling a greater number .of rods to .be threaded withoutresharpening of the threading tool.

Another object of the invention is the provision of a .new and improvedshock absorber construetion including a piston rod and a two-part pistonmounted on the lower end thereof, the piston rod having .a transversecircumferentially extending groove spaced from the lower end in which anupper :disclike part of the piston is positioned and may abut againstthe upper wall of the groove around substantially the entirecircumference thereof whereby to prevent cocking or tilting of the partwhen assembled on therod.

Another object of the invention is the provision of a new and improvedshock absorber including a piston rod and a two-part piston mounted onthe lower end thereof, the piston rod having a groove adjacent the lowerend for receiving an upper part of the piston, the portion of the pistonrod between the groove and the lower end. and the upper part .of thepiston being so formed that a central opening in the part may be of ,a

dimension whereby fluid passagesradially outwardly from the centralopening maybe of greater area and symmetrically positioned forfacilitating the flow of hydraulic shock absorber fluid thereby.

Another object of the invention is the provision of a new and improvedshock absorber construction including a piston rod and a two-part pistonmounted on the lower end thereof, the rod having a groove spaced fromthe lower end with the portion of the rod between the groove and the endbeing threaded to a uniform depth of threaded groove, the upper part ofthe piston comprising a disclike member having a central opening of lessdiameter than the diameter of the rod, which opening is threaded forpassage over the threaded end of the rod for positioning in the groove,the lower part of the piston having a central threaded aperture forthreaded engagement with the rod into abutting relationship with theupper part whereby to form the completed piston in firmly assembledrelationship.

The invention resides in certain constructions and combinations andarrangements of parts, and further objects and advantages will beapparent to those skilled in the art to which it relates from thefollowing description of the preferred embodiment described withreference to the accompanying drawings forming a part of this away inpart to show the piston and piston rod in elevation;

Fig. 2 is a fragmentary sectional view on a larger scale than Fig. 1through the work cylinder of the shock absorber shown in Fig. 1, thepiston being broken away to show the construction thereof in greaterdetail;

Fig. 3 is a perspective elevational view of a member forming an upperpart of the piston;

Fig. 4 is a fragmentary sectional view of the lower end of the pistonrod with the member shown in Fig. 3 in assembled relationship thereiwith;

Fig. 5 is a perspective elevational view of a packing ring carrier forthe piston packing;

Fig. 6 is a perspective elevational view of the I packing ring; and Fig.7 is a top elevational view of a member forming a body part of thepiston.

A shock absorber embodying the present invention is illustrated in thedrawing and is, by Way of example, a direct double-acting tubulartelescoping hydraulic shock absorber of the type shown and described inthe aforementioned patcut and patent application. Only those parts ofthe shock absorber which are necessary to a complete understanding ofthe present invention are herein shown and described in detail.Reference to the aforementioned patent and patent lapplication is madefor a complete showing and description of those parts of the shockabsorber not fully shown and described.

Referring to the drawings, the shock absorber shown comprises asubstantially cylindrical casing l5 which has relative telescopingmovement Within a cylindrical guard housing It that is spaced radiallyoutwardly from the casing 15.

The upper end of the housing [6 is closed by an inverted cup-shapedclosure or cap member I! provided on its outer side with an eye i8 whilea piston rod I9 is operatively connected to the cap member I! and eye18. The lower end of the casing I5 is closed by a cup-shaped closuremember 20 which has secured to its outer side a lower eye 2|. Theclosure members H and 20 extend into the housing I 6 and the casing I5,respectively, and are secured thereto by welding or by other suitablemeans.

In mounting the shock absorber upon a motor vehicle, similar mountingpins or trunnion rods (not shown) may be connected, respectively, to theframe and axle of the vehicle in any suitable manner so as to extendoutwardly therefrom in parallel relationship and pass through the eyesI8 and 2|. These pins or rods may be operatively connected with the eyesl8 and 2| by suitable means, well known in the art, wherefore relativemovement between the frame and axle of the vehicle will cause relativetelescoping movement between the casing 15 and the housing [6 andrelative movement of the piston rod l9 and the piston secured thereto inthe pressure or working cylinder, as will be well understood.

A pressure or working cylinder 22 of the shock absorber is disposedwithin the casing l5 in spaced concentric relationship therewith so thatthe space defined by the casing 15, cylinder 22, closure member 20, anda closure member (not shown) for the upper end of the casing andcylinder constitutes a reservoir 23 for the oil or liquid or fluid inthe shock absorber.

The lower end of the cylinder 22 extends into the cup-shaped closuremember 20 and is secured thereto by suitable means understood in theart. The cylinder 22 slightly upwardly of the lower end has securedtherein a closure plate 24. The cylinder 22 below the closure plate 24is provided with an inwardly extending bead 24a which serves to retainthe closure plate in position, while the cup-shaped closure member 20 isprovided with a plurality of circumferentially spaced internal groovesor channels 24b which place the reservoir 23 in communication with thespace between the closure plate 24 and the bottom of the cup-shapedclosure member 20. The closure plate 24 may also be provided with eithera fixed or a valve controlled orifice (not shown) communicating thespace between the closure plate 24 and the cup-shaped closure member 20with the interior of the cylinder 22 and permitting hydraulic fluid topass therethrough with a restricted or limited flow upon reciprocationof the piston in the cylinder 22. The closure plate 24 is also providedwith a replenishing valve 240, the purpose of which is well understoodin the art.

The piston rod !9 spaced from its lower or inner end is provided with atransverse circumferentially extending annular recess or groove 26having a base 26a and upper and lower walls 26?), 260, respectively. Theportion of the piston rod l9 between the lower groove wall 260 isprovided with a helical thread forming groove 25, the inner or rootdiameter of which is preferably uniform and equal to or just slightlygreater than the diameter of the groove base 26a. The axial orlongitudinal width of the groove 26 is preferably greater than a pitchlength between the threads 25 such that when the threads 25 are formedby suitable cutting tools, the cuttin tools may complete their threadcutting operation by advancing into the metal free space of the groove,providing an increased tool life over that which would otherwise bepossible if the thread groove terminated short of the annular groove andthe cutting tool thus stopped its thread cutting op eration while stillimbedded in the metal.

The piston is preferably formed in two parts and comprises a body whichmay be formed in various ways, but in the embodiment shown is a diecasting. The piston body includes a lower and larger portion 2'! and anupper and reduced portion 28. The periphery of the lower portion 2! ofthe piston body is provided with a plurality aromas grooves during theimpact or compression stroke of the piston. The portion 21 above thegrooves 30 is of less diameter thantt-he internal diameter of thecylinder 22, wherefore an annular space 32 is provided between thecylinder and the peripheryof the upper end of the piston portion 21. r

In the present illustration eight of me'grooves 30 are shown, but itshould be understood that the number of these grooves or passages may beVaried.

The lower portion 21 of the piston body is provided with a counterbore.36, the wall of which is threaded as indicated at 31. The inner end ofthe counterbore .36, that is, the upper end ofthe portion 21 of thepiston body, is separated from the upper reduced or smaller pistonportion 28 by a wall 38 in the center of which is a bore 38communicating with the counterbore 36 and with a larger central {bore 42in the upper portion 28 of the piston body. The Wall 38 surroundingthebore 39 is provided with an annular impact valve seat boss projectinginto thecounterbore 36 and provided with three radially extendinggrooves or notches 4| angularly spaced circularly of the seat boss 40.The bore 39 is opened and closed to communication with the counterbore35 and thus the lower side of the piston by a valve member 4 la normallybiased to the closed-position by a spring 411). The notches 41 provide ableeding action past the valve member Ma upon movement of the pistonineither direction.

The upper part 28 of the piston body is provided with thepreviouslyreferred to central bore 42 which is threaded so that the threaded endof the piston rod 19 can be screwed into the bore 42 in uniting thepiston body to the piston rod. The upper portion 28 of the piston bodyis also provided radially outwardly of the bore 42 with a plurality ofcircularly spaced axially extending peripheral recesses or grooves 43which extend from the piston portion ,2] to .the end of the pistonportion 28. The recesses 43 are substantially semicircular in crosssection and are angularly spaced circumierentially of the piston portion28, there .being eight .of such recesses 11- lustrated herein. Therecesses .43 can be die cast or otherwise formed in the piston body. Thepiston portion 28 is provided with four radially extending ports 44 thatplace the lower end of the bore 42 into conmmunication with everyalternate one of the eight axially extending recesses 43.

The other part of the piston comprises a flat circular washerlike member45 having a plurality, and as shown six, circumferentially spaced arms46 extending radially outwardly from the outer periphery thereof. Thewasherlike member 45 has a central circular opening 41 therethrough, thediameter of which is less than the diameter of the piston rod Hi, thewalls of the opening having helical thread forming grooves 48 of thesame pitch as the threads 25 on the lower end of the piston rod IS. Thewasherlike member 45 has a width slightly less than the axial width ofthe groove 26 such that when it is positioned in the groove 25 as shownin Fig. 4 by first threading it over the threads 25, it will be free ofsuch threads, free to rotate in the groove and abut squarely against theupper groove wall 26b. The piston body as shown is threaded on the loweror inner end of the piston rod is with the upper .ring 50 as viewed inthe drawings.

6 "end. of the upper piston portion 28 in abutting engagement with thelower side of the washer 145. with the .constnuction shown, the upperside of the washerlike member 45 will then abut the upper groove wall26!: throughout substantially the entire circumferential extent thereofWherefore .cocking or tilting of the member relative to the axis ofthepiston rod ll :9 will be substantially prevented. The outer diameterof the circular 'portionozf the washerlikernember 4.5 is preferably onlyslightly greater than the diameter of the piston rod .18 whereforebecause :of the circumier-ential spacing of the radial arms 45 a maximumarea of passage is provided therethrough between the chamber above thepiston and the peripheral recesses or grooves 43.

The piston body and the washerlike member 45 may be assembled on thelower or inner end of the piston rod 19 .simply and without thenecessity of aligning the washerlike member with the :piston'body ,onthe assembly step. The lower side of the radial .arms 45 forms aninterrupted upper wall of a packing ring groove otherwise defined by theouter surface of the upper part 28 of the piston body as a base and theupper surface of the piston portion 2?! as the lower wall.

In the embodiment of the invention shown, a flexible packing and valvering 50 of normally circular cross section .and formed of any suitablematerial, such .as synthetic rubber for example, is mounted on a carrier5al which is slidable on the upper portion 28 of the piston body, thatis to say, in the packing ring groove just referred to. The carrier 5!is in the form of a ring of angular cross section having an arm 52- thatextends longitudinally or axially of the piston and which contacts thepiston portion 28 and slides therealong and a radially extending arm 6'3which overlies the upper axial side of the It will thus be seen that thering 50 moves with the carrier 51 toward and away-from the pistonportion 21 upon changes in direction of piston movement,

and that when the ring 50 is in the position shown in Fig. 1 it acts asa valve to close the space 32 and the passages or grooves tocommunication with the upper side of the piston. While the positionindicated in Fig. 2, said space and passages are open and are incommunication with the passages 43, thereby permitting a flow ofhydraulic fluid from the lower side of the piston of the shock absorberto the upper side thereof. A coil spring 54 is mounted on the pistonportion 28 and abuts at its ends the radial arms 46 of the washer andthe carrier 5| and exerts pressure on the carrier toward the portion 21of the piston body, normally biasing the ring to the valve closedposition. The ring 53 and carrier assembly are movable as a unit upon asufficient differential in hydraulic pressure being developed during theimpact stroke of the piston on opposite sides of the ring 50 to overcomethe force of the spring 54.

The radially extending arm 53 of the carrier 5| generally undulatesaxially in a circumferential direction to form a plurality of alternatethe cross-sectional diameter of the ring 50. The

-upward or recoil stroke. ment of the piston, however, the portions ofthe ring 50 is preferably flat in its normal and unton portion 21providing a fluid seal, preventing flow of hydraulic fluid from thepassages 43 to the passage 30 and thus past the piston on the Uponopposite movering 50 opposite the axially displaced portions 531) maymove upwardly away from the piston portion 21 slightly opening thepassages 30, 43 to restricted bleeding communication through spacedcutaway portions 52a in the lower edge placed fiats 53b.

Thus it will be seen that an embodiment vof the invention has beendescribed which accomplishes the objects of the invention hereinbeforereferred to and others. It is not believed necessary to specificallydescribe a cycle of operation of the shock absorber disclosed hereinsince the manner in which the various parts of the shock absorberfunction is well understood and described in the art, particularly intheaforesaid patent and patent application. Sufiice it to say that thepresent construction offers less restriction to the flow of fluid pastthe piston allowed by the valve actions, as well as simplifying thestructure, facilitating assembly, and decreasing the cost ofmanufacture.

Although in accordance with the provisions of the patent statutes thisinvention is described as embodied in concrete form and the principlethereof has been described together with the best mode in which it isnow contemplated applying that principle, it will be understood that theapparatus shown and described is merely illustrative and that theinvention is not limited thereto, since alterations and modificationswill readily suggest themselves to persons skilled in the art withoutdeparting from the true spirit of this invention or from the scope ofthe annexed claims.

1 Having thus described my invention, I claim:

1. In a shock absorber of the direct doubleacting type having acylinder, a piston having a larger portion slidable in said cylinder andprovided with peripheral passages extending from end to end of saidportion and a smaller portion extending from one end of said largerportion and spaced radially inwardly from said cylinder and providedwith a central threaded bore, a packing ring movable on said smallerportion and engaging said cylinder, and spring means on said smallerportion and engaging said ring and urging it against said larger portionto close the said peripheral passages therein; the improvement whichcomprises a piston rod having an end connected to said piston, said rodbeing provided with a circular groove spaced from said end and withscrew threads extending from said groove to said end and screwed intosaid threaded bore, a disk-like member having a central threaded openingand screwed over said threaded rod end and into said groove, said memberbeing of such thickness as to be capable of free rotation in saidgroove, said member when said rod is fully screwed into said threadedbore being clamped against rotation between a wall of said groove andthe free end of said smaller piston portion and acting as an abutmentfor said spring means.

2. The improvement in a shock absorber as defined in claim 1 and whereinsaid improvement further consists in said disk-like member being in theform of a flat ring and having a series of circularly spaced radiallyextending arms projecting from the outer circumference of said ringwhile the inner circumference of said ring is screw-threaded and definesthe opening for said rod, said ring engaging the free end of saidsmaller piston portion and said arms also engaging the free end of saidsmaller piston portion and extending radially beyond the circumferenceof said smaller portion toward said cylinder and acting as the abutmentfor said spring means.

3. The improvement in a shock absorber as defined in claim 1 and whereinsaid improvement further consists in providing said one end of said rodwith threads, the inner or root diameter of which substantially equalsthe depth of said groove.

EUGENE L. BEECHER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,182,581 Casper Dec. 5, 19392,396,227 Beecher Mar. 12, 1946 OTHER REFERENCES Tool Engineering;Turning, Boring, and Grinding by Dowd 8: Curtis, first edition, pp. 164,165, and 257.

